Method of sheathing a stent

ABSTRACT

A method of sheathing a stent including the steps of providing a stent assembly including a catheter member and a stent member disposed about the catheter member; placing a first sheath film adjacent one side of the stent assembly; placing a second sheath film adjacent an opposite side of the stent assembly, and compressing the stent assembly, whereby the first and second sheath films move toward each other and substantially surround the stent assembly. The first and second sheath films are provided in rolls. Compressing is implemented by a radial compression mechanism. The first and second sheath films pass through the radial compression mechanism. Compressing sheaths the stent assembly and crimps the stent onto the catheter. As an alternative to two sheath films, a single film may be used, whereby compressing surrounds the stent assembly with the single sheath film. Also disclosed in an apparatus for sheathing a stent, including a compressing mechanism; a sheath film supply; a film feeder for moving at least one sheath film from the film supply through the compressing mechanism, and a stent input system for moving a stent assembly into the crimping mechanism.

CROSS-REFERENCE TO RELATED APPLICATIONS, IF ANY

This application claims the benefit under 35 U.S.C. §119(e) of U.S.Provisional Patent Application Ser. No. 60/624,432, filed Nov. 2, 2004,which is hereby incorporated by reference.

37 C.F.R. §1.71(e) AUTHORIZATION

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the US Patent and TrademarkOffice patent file or records, but otherwise reserves all copyrightrights whatsoever.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX, IF ANY

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates, generally, to medical apparatus ordevices, processes for making such apparatus, and apparatus for makingsuch apparatus and practicing such processes. Particularly, theinvention relates to medical stents. and stent manufacturing processesand apparatus. Most particularly, the invention relates to methods andapparatus for sheathing a stent, and a sheathed stent. Sheathing a stentis useful to protect the stent surface. Sheathing is particularly usefulfor protecting the stent during crimping or other processing. Sheathingis most particularly useful for crimping relatively sensitive drugcoating, polymer, biodegradable, or any material that can be easilydamaged from the crimp process stents. This process includes damagecaused from low force crimping on soft materials or high force crimpingon very hard materials. The apparatus, and manufacturing methods andapparatus therefor may be useful in other areas.

2. Background Information

The state of the art, in general, includes stents (including drug coatedstents) and stent making and crimping methods and apparatus. At present,there are a number of problems in crimping coated stents which occurbecause the coating is typically soft and somewhat fragile. One solutionis to place a thin sheath over the stent prior to crimping. The sheathis typically a thin (0.001-0.002 inch) walled tube which is placed byhand over the stent. The assembly is then placed in a crimping apparatusand the assembly is processed as normal. The sheath is then removed fromthe stent, again by hand, after crimping. This technology is believed tohave significant limitations and shortcomings. Hand placement andremoval of the sheath is a time consuming and expensive procedure. Also,tubular sheaths are typically expensive and difficult to apply.

For this and other reasons, a need exists for the present invention.

All US patents and patent applications, and all other publisheddocuments mentioned anywhere in this application are incorporated byreference in their entirety.

BRIEF SUMMARY OF THE INVENTION

The invention provides a method of sheathing a stent, particularlyduring a crimping process, and an apparatus for sheathing a stent, inparticular during a crimping process, which are practical, reliable,accurate and efficient, and which are believed to fulfill the need andto constitute an improvement over the background technology.

In one aspect, the invention provides a method of sheathing a stentcomprising the steps of providing a stent assembly including a cathetermember and a stent member disposed about the catheter member; placing afirst sheath film adjacent one side of the stent assembly; placing asecond sheath film adjacent an opposite side of the stent assembly; andcompressing the stent assembly, whereby the first and second sheathfilms move toward each other and substantially surround the stentassembly.

In an alternative method aspect, the invention provides a method ofsheathing a stent comprising the steps of providing a stent assembly;placing a first sheath film having a first edge and a second edgeadjacent the stent assembly in a predetermined configuration; andcompressing the stent assembly, whereby the sheath film surrounds thestent.

In another aspect, the invention provides an apparatus for sheathing astent, comprising a crimping mechanism; a sheath film supply; a filmfeeder for moving at least one film from the film supply through thecrimping mechanism, and a stent input system for moving a stent assemblyinto the crimping mechanism. The sheath film may comprises a single filmwhich is folded to substantially surround the stent assembly or a pairof films which are moved together to substantially surround the stentassembly. Folding or moving the film(s) preferably occurs duringactuation of the crimping mechanism.

The features, benefits and objects of the invention will become clear tothose skilled in the art by reference to the following description,claim(s), if any, and drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 illustrates an embodiment of the sheathed stent assembly of thepresent invention.

FIG. 2 is an end view of the assembly shown in FIG. 1.

FIG. 3 is a perspective view of an embodiment of an integrated filmcrimping apparatus of the present invention for sheathing a stentassembly during crimping.

FIG. 4 is a front view of the apparatus.

FIG. 5 is a back view of the apparatus.

FIG. 6 is a top view of the apparatus.

FIG. 7 is a bottom view of the apparatus.

FIG. 8 is a right side view of the apparatus with respect to the front.

FIG. 9 is a left side view of the apparatus.

FIG. 10 is a front view of the apparatus with the head opened for filmloading.

FIG. 11 is a back view thereof.

FIG. 12 is a detailed frontal view thereof.

FIG. 13 is a further detailed frontal view thereof.

FIG. 14 is a detailed back view thereof.

FIG. 15 is a further detailed back view thereof.

FIG. 16 illustrates an alternative embodiment of the sheathingapparatus.

FIG. 17 is a further perspective view thereof.

FIG. 18 illustrates another alternative embodiment of the sheathingapparatus, with its head opened.

FIG. 19 is a view of the apparatus with its head closed.

FIG. 20 is a detailed view of the head.

FIG. 21 is a still further detailed view of the head sheathing andcrimping a stent on a catheter.

FIG. 22 illustrates another embodiment of the sheath assembly andsheathing method of the invention, including a stent assembly with asingle film sheath.

FIG. 23 is an end view thereof.

DETAILED DESCRIPTION

The sheathing process and apparatus of the present invention utilize apair of flat films of material. No tubular sheath is required as in theprior art. Referring to FIGS. 1 and 2, a sheathed stent assembly 10,comprises a catheter body 11 and a stent 12, with a first or upper 13and a second or lower 14 flat film, ribbon, or half sheath. The films 13and 14 are disposed on each side of the stent 12, for example a drugcoated stent, also commonly called a drug eluting stent (DES). The films13 and 14 are preferably automatically fed into one side of a crimp head(See later Figures) in continuous paths. The paths pass through and outthe crimp head. The sheaths 13 and 14 protect the stent 12 during acrimping process. The continuous paths eliminate the need to manuallyhandle the stent/catheter assembly 10 in order to place a sheath. Filmmaterial, preferably flat, and in a continuous or endless roll or web islower cost than individual tubular sheaths. Film material is alsoavailable in thinner sizes, which improves process control.

A preferred, general embodiment of the method of sheathing a stent 12comprises the steps of providing a stent assembly including a cathetermember 11 and a stent member 12 disposed about the catheter member 11;placing a first sheath film 13 adjacent one side of the stent assembly11/12; placing a second sheath film 14 adjacent an opposite side of thestent assembly 11/12; and compressing, for example by crimping, thestent assembly 11/12, whereby the first and second sheath films 13 and14 move toward each other and substantially surround the stent assemblyas the stent 12 is crimped to the catheter member 11.

FIGS. 3-9 show an embodiment of the integrated film crimping apparatus20 of the present invention for sheathing and crimping a sent to acatheter. The apparatus 20 generally comprises a crimper 21, a mountingframe 22 connected to the crimper 21, a lower film roll or payoff 23 andan upper film roll 24 both connected to the frame 22, a take up spool 25connected to mount 22, and a separation system 26 also connected to themount 22 and the crimper 21.

The crimper 21 preferably functions generally as a segmental radialcompression system as described in U.S. Pat. No. 6,629,350 toMotsenbocker entitled Stent Crimping Apparatus and Method. However, thecrimper 21 is constructed and arranged to split or open to permit filmto pass through it's central aperture to thereby surround and sheath astent and catheter operatively placed for crimping. The crimper 21comprises a pair of crimp head members 32 and 33. Each member 32 and 33comprises a plurality of segments or elements 31. The elements arepreferably movably connected to a distal hub assembly 35/36-, which isconnected to an actuation arm 34. The actuation arm 34 may be disposedon both sides of the apparatus 10 or on one side. Other actuation meansare useable.

Top member 32 also comprises a top proximal pin plate assembly 41connected to a top plate 40. Bottom member 33 comprises a bottomproximal pin plate assembly 43 connected to a bottom plate 42.

Separation cylinder assembly 26 preferably comprises cylinders which aremounted to the mount 22 and to the top plate. Take up spool 25 isdriven, preferably by motor 50 and pulls film from the payoffs 24 and 23through the crimper 21.

FIGS. 10-15 show the head in an open position with lower and upper film51 and 52 passing through slot 53.

In use, the head 30 is opened by actuating the separation cylinder 26 toseparate the member 32 and 33, film is pulled from the payoffs 23 and 24over the gap between the members 32 and 33 and up to the takeup spool25. The head 30 is closed by actuating the separation cylinder to bringthe members 32 and 33 together. A stent is preferably relatively looselyplaced on a catheter. The stent catheter assembly 10 is placed on aninput assembly 54, and thereafter loaded in the crimp head 30 centralaperture 37, which is open a predetermined amount. In thisconfiguration, the upper and lower films surround the stent/catheterassembly 10. Referring to FIG. 21, the crimper 30 is actuated tosegmentally radially compress and crimp the stent onto the catheter. Thecrimper 30 releases to permit removal of the crimped stent, and thetakeup spool actuates to pull a fresh segment of upper and lower filminto the crimp aperture. The apparatus 10 is preferably controlled by anelectronic control mechanism 55.

FIGS. 16 and 17 and FIGS. 18-20 show an alternative embodiments 60 and70 of the integrated film crimper for sheathing and crimping that showthe film feed-in and take-up modifications. The apparatus 60 forsheathing a stent, also comprises a crimping mechanism; a sheath filmsupply; a film feeder for moving at least one film from the film supplythrough the crimping mechanism, and a stent input system for moving astent assembly into the crimping mechanism. The sheath film maycomprises a single film which is folded to substantially surround thestent assembly or a pair of films which are moved together tosubstantially surround the stent assembly. Folding or moving the film(s)preferably occurs during actuation of the crimping mechanism.

The shape of the upper and lower sheath halves are formed by the guideplates 61-64 illustrated in the crimp head. The two halves arecompressed by the crimping and sheathing head to form a tube likestructure which substantially completely sheaths the stent assemblyduring crimping of the stent on to the catheter. The “wings” of thesheath films pass through gaps between the crimp head segments.

Again, thin films of sheath material are stored on the front spools andare feed over the guide plates, through the crimp head and over of theguide plates on the opposite side of the head. The film is thencollected on take up spools on the opposite side of the crimp head. Thefilm paths are continuous, which eliminates the need to handle sheathmaterial except for initial loading of the machine. Several thousandstents can be sheathed and processed with one spool of sheath material.

Sheathing protects the drug coating on the stent, or sensitive non-drugcoated stents from handling errors. Sheathing also protects the drugcoating from wiping or shear during the process of crimping the stent ona delivery or other catheter. Automatic film sheathing eliminates orminimizes costly manual processing, and damage due to misalignment,cross contamination. Such sheathing also ensures one time contact withstents.

Referring to FIGS. 22 and 23, another approach to the film sheathassembly 15 is to use a single film 17 formed into a “keyhole” form. Thestent 16 protection and “wing” treatment is substantially the same asthe double film version. In this alternative embodiment of the method,the steps of the invention comprise providing a stent 16 assembly;placing a first sheath film 17 having a first edge and a second edgeadjacent the stent assembly in a predetermined configuration; andcompressing the stent assembly, whereby the sheath film surrounds thestent.

The descriptions above and the accompanying drawings should beinterpreted in the illustrative and not the limited sense. While theinvention has been disclosed in connection with an embodiment orembodiments thereof, it should be understood by those skilled in the artthat there may be other embodiments which fall within the scope of theinvention as defined by the claims. Where a claim, if any, is expressedas a means or step for performing a specified function it is intendedthat such claim be construed to cover the corresponding structure,material, or acts described in the specification and equivalentsthereof, including both structural equivalents and equivalentstructures, material-based equivalents and equivalent materials, andact-based equivalents and equivalent acts.

1. A method of sheathing a stent comprising the steps of: (a) providinga stent assembly including a catheter member and a stent member disposedabout the catheter member; (b) placing a first sheath film adjacent oneside of the stent assembly; (c) placing a second sheath film adjacent anopposite side of the stent assembly, and (d) segmentally radiallycompressing the stent assembly, whereby the first and second sheathfilms move toward each other and substantially surround the stentassembly; and wherein segmental radial compressing is implemented by asegmental radial compression mechanism having a plurality of segmentsdefining a central compression aperture having a longitudinal axis andconstructed and arranged to split to permit passage of the first andsecond sheath films.
 2. The method of claim 1, wherein the stentassembly has a longitudinal axis and wherein the first and second sheathfilms are provided in rolls and are placed by continuous feeding fromthe rolls to one lateral side of the stent assembly.
 3. The method ofclaim 1, wherein the first and second sheath films pass through alateral side of the segmental radial compression mechanism.
 4. Themethod of claim 3, wherein compressing sheaths the stent assembly andcrimps the stent onto the catheter, and wherein the stent is a balloonexpandable stent.
 5. A method of sheathing and crimping a balloonexpandable stent having a longitudinal axis, comprising the steps of:(a) providing a stent assembly including a catheter member and a stentmember disposed about the catheter member; (b) placing a first sheathfilm adjacent one side of the stent assembly; (c) placing a secondsheath film adjacent an opposite side of the stent assembly, wherein thefirst and second sheath films are provided in rolls and are placed byfeeding from the rolls to a lateral side of the stent assembly, and (d)segmentally radially compressing the stent assembly, whereby the firstand second sheath films move toward each other and substantiallysurround and crimp the stent assembly, wherein segmental radialcompressing is implemented by a segmental radial compression mechanismhaving a plurality of segments defining a central compression aperturehaving a longitudinal axis and constructed and arranged to split topermit passage of the first and second sheath films, and, wherein thefirst and second sheath films pass through a lateral side of thesegmental radial compression mechanism.